Is Labour really on the slide in London?

An opinion poll published last week found that the Conservatives have dramatically closed the gap on Labour in London from 16 percentage points to just three over the past year and that the Liberal Democrats have revived, doubling their support from seven points to 14. There’s been much coverage of Jeremy Corbyn’s negative score as Labour leader among the capital’s voters – a dreadful -44%. By contrast, Theresa May’s approval rating was a healthy +9% and that of Labour London Mayor Sadiq Khan a buoyant +35%.

What might the findings of the poll, conducted by YouGov for Queen Mary University of London (QMUL), mean for London politicians of all parties as they anticipate elections that lie ahead? Are they as gloomy for Labour and as heartening for some of their rivals as they at first appear? Is London’s recent standing as “a Labour city” likely to change over the next three years? Here are some tentative thoughts:

The poll can only be interpreted as showing Londoners losing faith in Labour as a potential party of national government. This should be particularly worrying for Corbyn given that he and the highest-profile members of his shadow cabinet – John McDonnell, Diane Abbott, Emily Thornberry and Keir Starmer – are all London MPs and that Labour actually gained seats in London at the 2015 general election despite losing badly nationally. It might not have helped that Corbyn and McDonnell have indulged in a bit of London-bashing lately, presumably in the hope of shoring up Labour’s support north of Watford.

The poll’s results will certainly be worrying for Labour politicians contesting next May’s borough elections and, looking further ahead to the 2020 general election, for London Labour MPs in marginal seats. It might even give Mayor Khan a ripple of concern should he be anticipating seeking a second mayoral term in the mayoral election scheduled to be held on the same day. When more than one election is held on the same day there is a tendency for voters to put a cross in the box of all the candidates representing the party they prefer, whatever job they are running for. If Corbyn leads Labour into the 2020 general election, Khan might suffer accordingly.

Of course, Jeremy Corbyn might stand down as Labour leader before the next general election or even later this year, which could make a difference. But if he doesn’t, what then…?

Local elections are often used to punish parties for their national performance – that’s what will be worrying Labour borough politicians and exciting Tories and Lib Dems as they look ahead to May 2018. However, results from borough by-elections in London might be signs that things need not turn out as badly for Labour next year as the poll indicates.

In March the party increased its vote share by 13.7% when holding a council seat in Harrow. In the period between Corbyn retaining the leadership last September and the end of last year, Labour’s vote share rose in six out of seven borough by-elections held during that time and stayed the same in the seventh, giving an average increase of 8.9% during those months. This has been in marked contrast with such elections in most of the rest of the country and an improvement on Labour’s London council by-election vote shares during the first year of Corbyn’s leadership (when they also went up, though only by a little). It would be perilous to read too much into these little local outcomes, not least because only the more committed voters turn out for them and there has only been the one in London so far this year. However, they might at least demonstrate that Labour’s ground operation in the capital remains formidable.

Might these by-election performances show that at least some London voters will continue to support Labour in full council elections even if they’ve gone off them as a national government option? In other words, could Labour’s vote hold up, or even improve, next May in spite of Corbyn’s poor ratings, assuming he is still Labour leader by then? This does not seem impossible. For example, Labour gained control of nine additional London boroughs in 2010, taking their total to 17, even though the Conservatives gained parliamentary seats in London in the general election held on the same day.

And what about 7 May 2020, when both a general and a mayoral election are due? If we assume, for the sake of argument, that Labour – whoever leads it by then – still has a narrowed poll lead in London, the Conservatives and Lib Dems will be justifiably optimistic about picking up seats here. But would Khan, if seeking a second term, be vulnerable?

Clearly, were Labour still weakened it wouldn’t help a Labour mayoral candidate. But we know from past mayoral elections that mayoral candidates can outperform their parties and vice versa. A good comparison is between first preference votes cast for named mayoral candidates and votes cast on the same day for the eleven “London-wide list” London Assembly members who are unnamed on the relevant ballot paper and chosen on the basis of their party.

The 2012 London elections make the point particularly well. That year, Conservative candidate Boris Johnson received 44% of first preference votes but the Conservative Party’s “list” candidates received only 32% of the London-wide Assembly member votes. By contrast, Labour’s Ken Livingstone secured 40.3% of mayoral first preference mayoral votes while his party’s “list” candidates got 41.1%. In other words, Johnson hugely outperformed his party while Livingstone did a little less well than his. The so-called “Boris bonus” more than cancelled out London voters’ general preference for Labour.

A striking thing about Khan’s rating in the YouGov/QMUL poll is how well he is regarded by Tory and Lib Dem supporters as well as Labour’s. We should mindful that incumbent mayors enjoy the luxury of having no equivalent to parliament’s leader of the Opposition to be compared with. Even so, at this point in the election cycle, Khan looks as though he’d take a lot of beating in 2020 whatever the state of Labour in London or anywhere else. We shall see.

Conclusion? The poll is undoubtedly encouraging for the Conservatives and the Lib Dems. So have been some London local election results, even as Labour’s support in them has held up or strengthened. Yet various bits of evidence from various kinds of election results suggest that a straight read-across from the new poll about Labour’s fortunes in London would be premature. They indicate that a significant part of the London electorate can and does vote for candidates from different parties in different types of elections, even if they are held on the same days. This is something all parties need to keep in mind. And might it be just one of the many ways in which London is different, generally? Read the full fieldwork for the YouGov/QMUL poll via here.

On London is run by Dave Hill, formerly the Guardian's award-winning London commentator, and written by him and an array of fellow Londoncentrics. It aims to improve the quality of coverage of London politics, development and culture.